1. Field of the Invention
The present invention relates to a solid-state imaging device, a method of manufacturing the same, and an electronic apparatus where the solid-state imaging device is applied to a camera or the like.
2. Description of the Related Art
As a solid-state imaging device, a CMOS solid-state imaging device, a CCD solid-state imaging device, or the like are used. Particularly, since the CMOS solid-state imaging device has a low power source voltage and low power consumption, it is employed in a digital still camera, a digital video camera, and various mobile terminal devices such as a mobile phone with a built-in camera.
For example, the CMOS solid-state imaging device includes a pixel portion where photodiodes which are a photoelectric conversion portion and a plurality of pixels having a plurality of pixel transistors are regularly arranged in two dimensions and a peripheral circuit portion disposed around the pixel portion. As the plurality of pixel transistors, for example, a three-transistor structure including a transfer transistor, a reset transistor, and an amplification transistor or a four-transistor structure with a selection transistor added is used.
A typical CMOS solid-state imaging device is constructed by arranging a plurality of unit pixels, each unit pixel including a single photodiode and a plurality of pixel transistors as a group. Recently, as the number of pixels increases, and the pixels become finer, in order to widen the area of the photodiode by reducing the number of pixel transistors per unit pixel, a so-called pixel sharing CMOS solid-state imaging device has been developed where the pixel transistor is shared among a plurality of pixels (refer to Japanese Unexamined Patent Application Publication Nos. 2008-294218 and 2006-54276). In addition, in order to widen the area of the photodiode, a back-side illumination type CMOS solid-state imaging device has been developed where the back face of the substrate opposite to the side where a wire line layer is arranged is used as a light incident face (refer to Japanese Unexamined Patent Application Publication No. 2003-31785).
Further, the CMOS solid-state imaging device includes an isolation region for isolating each pixel or an element within the pixel. For example, it is known that an isolation region using an STI (Shallow Trench Isolation) structure or an impurity semiconductor layer separates the photodiodes in the periphery of the pixel transistor for isolation (refer to Japanese Unexamined Patent Application Publication Nos. 2009-16810 and 2008-205022).